Design of a photonic crystal fiber with low confinement loss and high birefringence

A photonic crystal fiber (PCF) for long distance communication was proposed in this paper. The circular and elliptical air holes distribute in the cladding, and there are two small elliptical air holes around the core in cross section of the PCF. The characteristics of the PCF were analyzed by using the finite element method (FEM) sys-tematically. The results show that the PCF offers an ultrahigh birefringence of 3.51×10-2 and the confinement loss as low as 1.5×10-9 dB/m with the optimal structure at the wavelength of 1550 nm. Compared with the existing photonic crystal fibers with elliptical air holes, the birefringence has a large increase, and the confinement loss reduces by 5 orders of magnitude. Additionally, we also analyzed the relationship between the dispersion of the PCF and the wavelength, and obtained the Brillouin gain spectrum characteristics. In general, the PCF can be used in long distance communication system.